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Germ Warfare at Home
May 04, 2000

Everyone’s heard about food poisoning outbreaks from contaminated meat or poultry, yet most people don’t realize that we pick up most of these bugs right in our own homes. What’s more, in spite of a seeming flood of antibacterial products, food poisoning and respiratory illnesses are on the rise.

The reason may be that we’re not concentrating on the places where germs are found, according to Chuck Gerba, a microbiologist at the University of Arizona. Gerba has gone into people’s homes to study how and where they clean, and come up with some surprising results.

Where have all the germs gone?

Gerba and his team went into 14 homes in Arizona and measured different kinds of microbes, such as fecal coliform bacteria, in their kitchens and bathrooms. These fecal bacteria aren’t always harmful, but they are a good indicator of contamination.

Microbes image

"Most people don’t realize that in our studies of homes we find the greatest number of fecal bacteria actually in your kitchen sink, and the least number in your bathroom," says Gerba. There are actually 200 times more fecal bacteria on a the average person’s cutting board than on a toilet seat, he notes.

Sponges or dishcloths are a germ’s favorite place to live, with 600,000 bacteria per square centimeter. The area around the kitchen sink drain comes in second, followed by the bathroom sink drain. Kitchen tap handles come in fourth, and the refrigerator door handle is the fifth most likely place to find bacteria.

Oddly enough, the top of the toilet seat is the last place germs hide, with just 0.5 bacteria per square centimeter. "If I were an alien microbiologist and looked at that data I’d be confused where the bathroom was," says Gerba.

The Sponge

Here are some good ways to keep the home’s #1 microbe threat at bay:

•Replace it frequently.

•Microwave your sponge or dishrag for 30 seconds.

•Put it through the dishwasher.

•Use germ-resistant sponges.

Finding microbes in the kitchen isn’t really surprising, considering that most people tend to use germ-killing cleaners in the bathroom, but not in the kitchen. This means that bacteria from raw meat products and produce tend to get spread around instead of killed. The moisture and microscopic bits of food found in sponges and sinks also makes them attractive breeding grounds for bacteria. "The best friend a germ ever had is a hand," says Gerba, "because you bring your fingers to your nose or mouth." That’s why frequent contact with sink tap handles makes it easy for germs to spread from hands to kitchen surfaces or people.

Other surfaces in the kitchen, such as cutting boards and stainless steel, can harbor bacteria as well. Even a surface that appears smooth may have tiny nicks and dents that microbes can’t resist. "We’re literally playing Russian Roulette with every surface we touch," says Gerba.

How can I get rid of bacteria?

Studies by Edmund Zottola at the University of Minnesota in St. Paul have shown that bacteria produce an organic substance that cements cells to surfaces, allowing them to survive even if they’re sprayed with water or washed with a weak detergent solution. Gerba’s advice is to make sure to target bacteria hotspots with cleaners that use the word "disinfect," which is a legal term that means the product will kill both bacteria and viruses that can cause illness. Home remedies like vinegar and ammonia won’t work, but bleach, which ironically has been around for hundreds of years, will do the trick. It’s important to dry surfaces after they’ve been sanitized, though.

"You don’t have to sanitize your house, you just have to be germ-wise in your house and pick those certain germ hot zones and make sure those are the areas you really clean with disinfectant cleaners," Gerba says.

Next on his list is studying other places in the home that people constantly touch -- like telephones and doorknobs. "How often do you touch a doorknob with the common cold virus on it?" wonders Gerba. "Nobody really knows that."

Reason for Caution

According to the Centers for Disease Control and Prevention, during the last 15 years, several diseases whose causes were unknown have turned out to be complications of foodborne infections. One example is Guillain-Barre syndrome, which can be caused by an infection from Campylobacter. Also, E. coli 0157:H7 has been discovered to be the most common cause of acute kidney failure in children. Who knows what other diseases will turn out to be linked to foodborne infections?

Elsewhere on the web:

Can your kitchen pass the food safety test?

Common foodborne pathogens

Types of bacteria found on sinks and faucets

USDA Guide to Safe Food Handling

How to Keep Germs Away

by Jill Max

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